1. Field of the Invention
The present invention relates generally to an apparatus and a method for a repeater in a wireless communication system. More particularly, the present invention relates to an apparatus and a method for a repeater using a multi-antenna in a wireless communication system.
2. Description of the Related Art
As the wireless communications market has grown, wireless communication systems have evolved to provide multimedia services. When providing multimedia services, wireless communication systems transmit large amounts of data at a high data rate. In an effort to more efficiently utilize the limited frequency resources, a multi-antenna scheme (e.g., Multiple Input Multiple Output (MIMO)) is being developed.
Using a multi-antenna, a wireless communication system sends signals by occupying channels so as to be able to extract the independent signals through the multi-antenna.
Wireless communication systems may have one or more shadow areas. A shadow area is an area where the sensitivity of radio waves is weakened or the propagation of radio waves is limited. The shadow area may be caused by high buildings, entangled roads or the like. If a terminal serviced by a base station travels into a shadow area, the terminal cannot provide normal service because of the low power level of the signal received from the base station. To address the shadow area, the wireless communication system may utilize a repeater.
A repeater amplifies the signal received from the base station and retransmits the amplified signal to terminals in the shadow areas so that the terminals can receive the signal with a sufficient level of power. The repeater also amplifies signals received from the terminals in the shadow area and retransmits the amplified signals to the base station so that the base station can acquire the signals from the terminals.
A conventional repeater is constructed as shown in FIG. 1.
FIG. 1 is a block diagram of a conventional repeater using a single antenna for communications with the terminals and another single antenna for communications with the base station. Hereafter, an exemplary Radio Frequency (RF) repeater is explained.
When receiving a signal from a base station 100 over a first antenna 120, the repeater 110 of FIG. 1 amplifies the received signal using a first amplifier 113. The repeater 110 transmits the amplified signal to terminals over a second antenna 130.
When receiving a signal from the terminals over the second antenna 130, the repeater 110 amplifies the received signal using a second amplifier 114. The repeater 110 transmits the amplified signal to the base station 100 over the first antenna 120.
The repeater 110 interconnects the antennas 120 and 130 and the amplifiers 113 and 114 using switches 111 and 115. For example, when the repeater 110 relays the signal of the base station 100, the first switch 111 connects the first antenna 120 to the first amplifier 113 and the second switch 115 connects the second antenna 130 to the first amplifier 113. When the repeater 110 relays the signal of the terminals, the first switch 111 connects the first antenna 120 to the second amplifier 114 and the second switch 115 connects the second antenna 130 to the second amplifier 114.
As discussed above, a wireless communication system may employ a repeater to address a shadow area. When implemented, the repeater relays the signals using a single antenna for communications with the terminals and another single antenna for communications with the base station. However, even when the wireless communication system adopts a multi-antenna scheme to increase the capacity and the data rate, the signal relayed by the repeater cannot increase the data capacity because the repeater still uses a single antenna for communications with the terminals and another single antenna for communications with the base station.